A laminating process method of a surface adhesive stator core

Abstract

The application discloses a laminating process method of a surface-gluing stator core. The method stacks multiple surface-gluing stator punching sheets with heat-curable adhesive layers to form a punching sheet group, heats the punching sheet group under a first axial pressure, and obtains variation data of a laminating height with time to determine a compression flow index; the high pressure is avoided from being applied before the compression flow index reaches a peak value, and a second axial pressure is applied to perform 2-8 times of pulsed short-time compaction when the compression flow index decreases from the peak value to a preset ratio; meanwhile, the boundary region and the main body bonding region of the punching sheet group are subjected to differential temperature control, so that the temperature of the boundary region is lower than that of the main body bonding region. After the pulsed short-time compaction, the differential temperature control is reduced or removed, and the heat preservation and curing and pressure maintaining and cooling shaping are performed. The method can control the pressure switching according to the actual flow state of the adhesive layer, reduces the risk of adhesive overflow at the end face, the inner circle, the outer circle and the tooth groove, and improves the laminating stability and forming quality of the surface-gluing stator core.

Description

Technical Field

[0001] This invention relates to the field of motor stator core manufacturing technology, and in particular to a lamination process method for a surface-bonded stator core. Background Technology

[0002] The stator core is a crucial component of the motor stator assembly, typically formed by stacking multiple stator laminations axially. To improve the connection stability between laminations and reduce the impact of traditional welding, riveting, or snap-fit ​​connections on the core's structural consistency and electromagnetic performance, existing technologies increasingly employ stator laminations with pre-applied adhesive layers on their surfaces for stacking. Under heating and pressurization, these laminations can bond adjacent laminations together, resulting in a stator core with a certain overall strength and stacking density.

[0003] Existing lamination processes for adhesive-coated stator cores typically employ hot-pressing curing at preset temperatures, pressures, and holding times. While this method achieves bonding between laminations, it relies heavily on fixed process parameters and fails to adequately account for the softening, flow, tackification, and curing changes of the adhesive layer during heating. Since different batches of adhesive-coated stator laminations may vary in adhesive layer thickness, activation state, storage conditions, and surface condition, fixing hot-pressing parameters can easily lead to fluctuations in the molding quality of different batches of cores.

[0004] In actual lamination, if a large continuous axial pressure is applied when the adhesive layer is in a low viscosity and easy flow stage, the adhesive layer is prone to overflow to the end face, inner circle edge, outer circle edge or tooth groove edge, affecting the core dimensional accuracy, end face cleanliness and subsequent assembly; if the pressure is reduced or the holding time is shortened to avoid adhesive overflow, it may lead to insufficient compaction between sheets, low lamination coefficient or unstable bonding strength.

[0005] Therefore, it is necessary to provide a surface adhesive stator core lamination process that can determine the pressure switching timing based on the actual flow state of the adhesive layer and constrain the flow in the easily overflowing adhesive boundary area. Summary of the Invention

[0006] To address the problems in existing adhesive stator core lamination processes that rely primarily on fixed temperature, pressure, and holding time for hot pressing curing, making it difficult to determine the pressure switching timing based on the actual flow state of the adhesive layer, which can easily lead to adhesive overflow, insufficient lamination coefficient, or poor batch stability, this invention provides an adhesive stator core lamination process method.

[0007] To achieve the above objectives, the present invention provides a lamination process for a surface-bonded stator core, comprising the following steps: Multiple surface adhesive stator laminations are stacked to form a lamination assembly. The surface adhesive stator lamination includes a stator lamination substrate and a thermosetting adhesive layer disposed on the surface of the stator lamination substrate. The lamination assembly is heated under a first axial pressure P1 and the stacking height H is obtained as a function of time t. The compressibility flow index I(t) is determined based on the change data. Before the compressibility flow index I(t) reaches its peak value Imax, the axial pressure P applied to the lamination group is kept less than the second axial pressure P2; When the compressibility flow index I(t) decreases from the peak value Imax to kImax, the second axial pressure P2 is applied to the stamping assembly for 2 to 8 pulsed short-time compaction cycles, where 0.20≤k≤0.60 and P2 is greater than P1; During at least a portion of the heating and pulsed short-time compaction process, the boundary region of the lamination group and the main body bonding region are subjected to differential temperature control, so that the temperature of the boundary region is lower than the temperature of the main body bonding region. The boundary region is the region adjacent to at least one of the inner circle edge, outer circle edge and tooth groove edge of the adhesive stator lamination. After the pulsed short-time compaction is completed, the axial pressure is adjusted to a third axial pressure P3, which is less than P2. The differential temperature control is reduced or eliminated, and the lamination assembly is subjected to heat preservation and curing. Under the condition of maintaining axial pressure, it is cooled and shaped to obtain the surface adhesive stator core. The temperature and time of the heat preservation and curing are determined according to the curing characteristics of the heat-curable adhesive layer. Preferably, the heat preservation and curing temperature is 140℃~210℃, and the heat preservation time is 10min~120min. During cooling and shaping, the lamination assembly is cooled to the preset demolding temperature and then the axial pressure is removed.

[0008] Furthermore, the compressibility flow index I(t) is determined according to the following formula: ; Alternatively, it can be determined in the following discrete form: ; Where Δt is the time interval between two consecutive overlay height acquisitions. Let H(t) be the first derivative of the stacking height H(t) with respect to time t. for The stacking height at any given moment.

[0009] Furthermore, before the compressibility flow index I(t) reaches its peak value Imax, the axial pressure P applied to the lamination assembly is less than or equal to 0.50P2.

[0010] Furthermore, the first axial pressure P1 is 0.05MPa to 0.50MPa, the second axial pressure P2 is 1.50MPa to 4.50MPa, and the third axial pressure P3 is 0.20MPa to 1.50MPa.

[0011] Furthermore, the duration of each pulsed short-time compaction is 1s to 20s; a low-pressure holding stage is set between two adjacent pulsed short-time compactions, wherein the axial pressure of the low-pressure holding stage is 0.20MPa to 1.00MPa, and the holding time is 5s to 60s.

[0012] Furthermore, the differentiated temperature control ensures that the temperature of the boundary region is 10°C to 40°C lower than the temperature of the main bonding region, and the width of the boundary region extending from the inner circle edge, outer circle edge, or tooth groove edge towards the main bonding region is 0.20mm to 5.00mm.

[0013] Furthermore, the differentiated temperature control is achieved through a boundary temperature control component, which includes at least one of an inner circle temperature control component, an outer circle temperature control component, and a toothed groove temperature control component; the inner circle temperature control component is disposed adjacent to the inner circle edge, the outer circle temperature control component is disposed adjacent to the outer circle edge, and the toothed groove temperature control component is disposed adjacent to the toothed groove edge.

[0014] Furthermore, the boundary temperature control component includes at least one of a cooling channel, a thermally conductive insert, a thermally insulating pad, and a local temperature control pressure block.

[0015] Furthermore, before the compressibility flow index I(t) begins to rise and reaches Imax, a small axial pulsating pressure or a small opening and closing displacement is applied to the lamination assembly under the condition of the first axial pressure P1 as the reference pressure; the pulsation frequency of the small axial pulsating pressure is 0.05Hz to 2Hz, and the number of pulsations is 3 to 30 times; the displacement of the small opening and closing displacement is 0.005mm to 0.050mm, and the frequency is 0.05Hz to 1Hz.

[0016] Furthermore, when changing the batch of stator laminations with adhesive surface, the lamination group formed by the new batch of stator laminations with adhesive surface is re-acquired with time t, and the pressure switching time corresponding to the peak value Imax and kImax is re-determined.

[0017] Compared with the prior art, the present invention provides a lamination process for a surface-bonded stator core, which has the following beneficial effects: 1. This invention obtains data on the change of stacking height H over time t and determines the compressibility flow index I(t), so that the pressure switching during the stacking process matches the actual flow state of the adhesive layer; high pressure is avoided before the compressibility flow index I(t) reaches the peak value Imax, and pulsed short-time compaction is performed after it drops from the peak value Imax to a preset ratio, so that the high-pressure compaction stage avoids the lowest viscosity or maximum flow stage of the adhesive layer, thereby reducing the risk of the adhesive layer overflowing under pressure.

[0018] 2. This invention differentiates the temperature of the boundary area and the main bonding area of ​​the lamination assembly, so that the temperature of the boundary area adjacent to the inner circle edge, outer circle edge or tooth groove edge is lower than the temperature of the main bonding area. This keeps the adhesive layer in the boundary area relatively high in viscosity, restricts the adhesive layer in the main bonding area from overflowing to the boundary, and helps to improve the cleanliness and dimensional stability of the iron core end face.

[0019] 3. This invention reduces or eliminates differential temperature control after pulsed short-time compaction, and performs heat preservation curing and cooling shaping while maintaining axial pressure, so that the boundary area can be cured. At the same time, it reduces the springback of the lamination and the fluctuation of the stacking height caused by hot pressure relief. This invention does not require changing the adhesive layer formula and coating structure of the existing surface adhesive stator lamination, and has good process adaptability. Attached Figure Description

[0020] Figure 1 This is a flowchart of the lamination process for the adhesive-coated stator core of the present invention; Figure 2 This is a schematic diagram showing the relationship between the compressibility flow index I(t) and the switching timing of axial pressure P in this invention. Where tmax is the moment when the compressibility flow index I(t) reaches its peak value Imax, tk is the moment when the compressibility flow index I(t) drops from its peak value Imax to kImax, 0.80Imax is used to represent the reference stage when the adhesive layer is close to the maximum flow state, and 0.20≤k≤0.60. Detailed Implementation

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] This invention provides a lamination process for adhesive-coated stator cores, applicable to the process of forming adhesive-coated stator cores by laminating multiple adhesive-coated stator laminations. The adhesive-coated stator lamination includes a stator lamination substrate and a thermosetting adhesive layer disposed on the surface of the stator lamination substrate. The thermosetting adhesive layer can be disposed on one side of the stator lamination substrate or on both sides of the stator lamination substrate, as long as it can bond adjacent stator laminations under heating and pressurization conditions.

[0023] This invention establishes a compressibility flow index I(t) to characterize the flow state of the adhesive layer by using data on the change in stacking height of the stamping assembly during the low-pressure heating process, and determines the high-pressure pressing time mechanism based on the compressibility flow index I(t); at the same time, a temperature difference is formed between the boundary area of ​​the stamping assembly and the main body bonding area, so that the adhesive layer in the boundary area maintains a relatively high viscosity, thereby limiting the overflow of the adhesive layer to the inner circle edge, outer circle edge or tooth groove edge.

[0024] In a preferred embodiment, the method of the present invention can be implemented using a stacking fixture. The stacking fixture may include an upper pressure plate, a lower pressure plate, an axial pressing mechanism, a heating mechanism, a stacking height acquisition mechanism, a boundary temperature control component, and a controller. The upper and lower pressure plates are used to clamp the stamping assembly and transmit axial pressure to it; the axial pressing mechanism is used to apply a first axial pressure P1, a second axial pressure P2, and a third axial pressure P3; the heating mechanism is used to heat and heat-cur the stamping assembly; the stacking height acquisition mechanism is used to acquire data on the change in the stacking height H of the stamping assembly over time t; the boundary temperature control component is used to control the temperature of the boundary area of ​​the stamping assembly; and the controller is used to determine the compressibility flow index I(t) based on the change data and control the switching of the axial pressure based on the compressibility flow index I(t).

[0025] In this invention, the main bonding area refers to the region between adjacent adhesive stator laminations that primarily forms inter-laminar bonding and withstands compaction. The boundary region refers to the region adjacent to at least one of the inner circle edge, outer circle edge, and tooth groove edge of the adhesive stator lamination. Since the boundary region is close to the location where the adhesive layer is prone to overflow, by making the temperature of the boundary region lower than that of the main bonding area, the viscosity of the adhesive layer in the boundary region can be relatively high, thereby forming a flow-blocking region that hinders the outward flow of the adhesive layer.

[0026] Specifically, the lamination process of the surface adhesive stator core described in this invention may include the following steps.

[0027] First, multiple adhesive-coated stator laminations are stacked to form a lamination assembly. Before stacking, the adhesive-coated stator laminations can be visually inspected and cleaned to remove laminations with obvious warping, damaged adhesive layers, adhesive layer contamination, abnormal burrs in the tooth grooves, or end face deformation. During stacking, the inner circle, outer circle, or tooth groove can be used as positioning references to ensure that the multiple adhesive-coated stator laminations are aligned radially and circumferentially. The inspection, cleaning, and positioning methods before stacking can be selected based on the structure of the adhesive-coated stator laminations and production conditions.

[0028] Then, the lamination assembly is heated under a first axial pressure P1, and the change in stacking height H over time t is acquired. The first axial pressure P1 is a low axial pressure, its function being to maintain stable contact between adjacent laminations and to allow the height change of the adhesive layer during heating to be collected, while avoiding excessive extrusion during the low viscosity stage of the adhesive layer. The stacking height H can be obtained using a displacement sensor, grating ruler, servo press displacement feedback signal, or other detection devices capable of reflecting changes in the upper pressure plate displacement.

[0029] The controller determines the compressibility flow index I(t) based on the change in stacking height H over time t. The compressibility flow index I(t) can be determined using the following formula: ; It can also be determined in the following discrete form: ; Where Δt is the time interval between two consecutive overlay height acquisitions. Let H(t) be the first derivative of the stacking height H(t) with respect to time t. for The stacking height at any given time. Since the stacking height of the lamination assembly typically decreases gradually during the softening, flow, and bonding of the adhesive layer, the above formula can be used to obtain the compressibility flow index, which characterizes the rate of change of the lamination assembly height under unit pressure. The larger I(t) is, the faster the height of the lamination assembly changes under low pressure, meaning the adhesive layer is in a more flowable state.

[0030] To reduce the impact of measurement noise on the judgment results, the stacking height H or the compressibility flow index I(t) can be smoothed. The smoothing process can be a moving average, median filtering, or low-pass filtering. For example, the average value can be calculated from 3 to 10 consecutive sampling points. When the smoothed I(t) changes from rising to falling, the I(t) corresponding to that position is determined as the peak value Imax. The peak value Imax can be used to characterize the maximum compressibility flow stage of the adhesive layer under the current heating conditions.

[0031] Before the compressibility flow index I(t) reaches its peak value Imax, the axial pressure P applied to the lamination assembly is kept less than the second axial pressure P2. Further, before I(t) reaches its peak value Imax, the axial pressure P applied to the lamination assembly is preferably less than or equal to 0.50P2. In a preferred embodiment, the stage where I(t) is not less than 0.80Imax can be considered as the stage where the adhesive layer approaches its maximum flow state, used to evaluate whether low-pressure control covers the high flow window of the adhesive layer. In this way, when the adhesive layer is in the low viscosity or maximum flow stage, the high axial pressure used for final compaction is not applied to the lamination assembly, thereby reducing the risk of adhesive layer overflow along the lamination end face, inner edge, outer edge, or groove edge.

[0032] When I(t) decreases from its peak value Imax to kImax, a second axial pressure P2 is applied to the lamination assembly for 2 to 8 pulsed short-time compaction cycles, where 0.20 ≤ k ≤ 0.60, and P2 is greater than P1. At this point, the adhesive layer has transitioned from the maximum flow stage to the tackification stage, but it is not yet fully cured and still has the ability to fill the tiny gaps between the laminations. Simultaneously, the tendency for it to continuously overflow towards the boundary area is reduced. Therefore, performing pulsed short-time compaction at this stage can balance the compaction effect of the lamination assembly with the effect of preventing adhesive overflow.

[0033] The pulsed short-time compaction refers to the compaction process in which a second axial pressure P2 is applied intermittently to the lamination assembly after the compressibility flow index I(t) decreases from its peak value Imax to kImax. The number of pulsed short-time compactions is 2 to 8, with each pulsed short-time compaction lasting from 1 to 20 seconds. A low-pressure holding phase is set between two adjacent pulsed short-time compactions, with an axial pressure of 0.20 MPa to 1.00 MPa and a holding time of 5 to 60 seconds. By alternating between pulsed short-time compaction and low-pressure holding, the outward extrusion effect of continuous high pressure on the adhesive layer can be reduced, and the adhesive layer can be redistributed between the laminations.

[0034] During at least a portion of the heating and pulsed short-time compaction process, the boundary region of the lamination assembly and the main bonding region are subjected to differentiated temperature control, ensuring that the temperature of the boundary region is lower than that of the main bonding region. Preferably, the temperature of the boundary region is 10°C to 40°C lower than that of the main bonding region, and the width of the boundary region extending towards the main bonding region along the inner edge, outer edge, or groove edge is 0.20mm to 5.00mm. This temperature difference maintains a relatively high viscosity in the adhesive layer of the boundary region, thereby hindering the outward flow of the adhesive layer in the main bonding region.

[0035] Differential temperature control can be achieved through boundary temperature control components. These boundary temperature control components can include at least one of an inner circle temperature control component, an outer circle temperature control component, and a toothed groove temperature control component. The inner circle temperature control component is disposed adjacent to the inner circle edge of the adhesive stator lamination, the outer circle temperature control component is disposed adjacent to the outer circle edge of the adhesive stator lamination, and the toothed groove temperature control component is disposed adjacent to the toothed groove edge of the adhesive stator lamination. The boundary temperature control component can include at least one of a cooling channel, a thermally conductive insert, a thermal insulation pad, and a localized temperature control block. For example, the boundary temperature control component can remove heat from the boundary area through a cooling channel, or it can conduct heat from the boundary area through a thermally conductive insert or a localized temperature control block, or it can reduce the heat transfer efficiency of the heating mechanism to the boundary area through a thermal insulation pad.

[0036] Before I(t) begins to rise and reaches Imax, a small-amplitude axial pulsating pressure or a small-amplitude opening and closing displacement can be applied to the lamination assembly under the condition of the first axial pressure P1 as the reference pressure. When using a small-amplitude axial pulsating pressure, the compressibility flow index I(t) can be determined based on the stacking height data collected when the first axial pressure P1 is used as the reference pressure. The pulsation frequency of the small-amplitude axial pulsating pressure can be 0.05Hz to 2Hz, and the number of pulsations can be 3 to 30. The displacement amount of the small-amplitude opening and closing displacement can be 0.005mm to 0.050mm, and the frequency can be 0.05Hz to 1Hz. Through the above-mentioned small-amplitude pulsation or small-amplitude opening and closing, the air discharge between the laminations and the initial wetting of the adhesive layer can be promoted, reducing the adhesive layer deviation caused by local air gaps during subsequent pulsed short-time compression. When performing small-amplitude opening and closing displacement, the lamination assembly can still maintain its radial and circumferential positions through the inner circle, outer circle, or toothed groove positioning structure to avoid lamination misalignment.

[0037] After the pulsed short-time compaction is completed, the axial pressure is adjusted to a third axial pressure P3, which is less than P2, and the differential temperature control is reduced or removed, allowing the boundary area to gradually reach the temperature required for the adhesive layer to cure. Subsequently, the lamination assembly is heat-cured and cooled and shaped while maintaining the axial pressure, resulting in a surface-adhesive stator core. The temperature and time of the heat-curing can be determined based on the curing characteristics of the heat-curable adhesive layer; preferably, the heat-curing temperature is 140℃~210℃, and the heat-curing time is 10min~120min. During cooling and shaping, the lamination assembly can be cooled to a preset demolding temperature while maintaining the third axial pressure P3 or a cooling pressure less than the third axial pressure P3, and then the pressure can be released. The preset demolding temperature can be a temperature not higher than the softening initiation temperature of the adhesive layer, or a temperature that allows the surface-adhesive stator core to maintain a stable stacking height after demolding.

[0038] In mass production, the pressure switching timing can be re-determined based on the differences in adhesive layer state between different batches of adhesive stator laminations. Specifically, when changing batches of adhesive stator laminations, S2 is repeated for the lamination group formed by the new batch of adhesive stator laminations. The laminations are heated under the first axial pressure P1, and the change in stacking height H over time t is obtained. Based on H(t), the pressure switching time corresponding to the compressibility flow index I(t), peak value Imax, and kImax is re-determined. This reduces pressure switching deviations caused by differences in adhesive layer thickness, storage conditions, or initial flowability between different batches of adhesive stator laminations.

[0039] The present invention will be further described below with reference to specific embodiments. Example 1

[0040] This embodiment provides a surface adhesive stator core stacking process applicable to conventional adhesive layer thickness and conventional lamination quantity.

[0041] Several stator laminations with adhesive backing from the same batch are taken. Each stator lamination includes a stator lamination substrate and a heat-curable adhesive layer on the surface of the substrate. Before stacking, the stator laminations are visually inspected and cleaned, and laminations with obvious warping, damaged adhesive layer, adhesive layer contamination, abnormal groove burrs, or end face deformation are removed. Subsequently, the stator laminations are sequentially stacked in a stacking fixture to form a lamination assembly. Inner circle, outer circle, or groove positioning structures are used to maintain radial and circumferential alignment of the multiple stator laminations.

[0042] The stacking fixture includes an upper pressure plate, a lower pressure plate, an axial pressing mechanism, a heating mechanism, a stacking height acquisition mechanism, a boundary temperature control component, and a controller. The stacking height acquisition mechanism uses a displacement sensor or a servo press displacement feedback device to collect data on the change of the stacking height H of the lamination group over time t. The boundary temperature control component includes at least one of an inner circle temperature control component adjacent to the inner circle edge, an outer circle temperature control component adjacent to the outer circle edge, and a tooth groove temperature control component adjacent to the tooth groove edge.

[0043] In this embodiment, the first axial pressure P1 is set to 0.30 MPa. The lamination assembly is heated under the first axial pressure P1, and the lamination height H of the lamination assembly changes with time t using a lamination height acquisition mechanism, with a sampling interval Δt of 1 s. The controller determines the compressibility flow index I(t) according to the following discrete form: .

[0044] To reduce the impact of sampling noise on the judgment results, the controller calculates a moving average value for five consecutive sampling points to obtain the smoothed compressibility flow index I(t). When the smoothed I(t) changes from increasing to decreasing, the I(t) corresponding to that position is determined as the peak value Imax.

[0045] Before I(t) reaches its peak value Imax, the axial pressure P applied to the lamination assembly is kept less than or equal to 0.50P2. In this embodiment, the second axial pressure P2 is set to 3.00 MPa. When I(t) drops from Imax to 0.40Imax, the axial pressure is increased to the second axial pressure P2 for pulsed short-time compaction.

[0046] In this embodiment, the pulsed short-time compaction adopts 3 pulsed compaction, each pulsed compaction lasts for 8 seconds; a low-pressure holding stage is set between two adjacent pulsed compaction, the axial pressure of the low-pressure holding stage is 0.60 MPa, and the holding time is 20 seconds.

[0047] During the heating and short-time compaction period, differential temperature control is applied to the boundary area and the main bonding area of ​​the lamination assembly, ensuring that the temperature of the boundary area is 25°C lower than that of the main bonding area. The boundary area includes a region adjacent to at least one of the inner circle edge, outer circle edge, and tooth groove edge of the stator lamination, and the boundary area extends 2.50 mm in width along the corresponding edge towards the main bonding area. This differential temperature control maintains a relatively high viscosity of the adhesive layer in the boundary area, thereby limiting the overflow of the adhesive layer from the main bonding area to the boundary area.

[0048] After the pulsed short-time compaction is completed, the axial pressure is adjusted to the third axial pressure P3, which is set to 0.90 MPa. Differential temperature control is reduced or removed to allow the boundary area to gradually heat up to the curing temperature range of the adhesive layer. Subsequently, the lamination assembly is subjected to heat preservation and curing at 180℃ for 40 minutes. After heat preservation and curing, the laminations are cooled to the preset demolding temperature while maintaining the third axial pressure P3, and then the pressure is released to obtain the adhesive-coated stator core.

[0049] In this embodiment, the maximum flow stage of the adhesive layer is determined by the compressibility flow index I(t), and short-term compaction is applied after I(t) drops from its peak value to 0.40Imax, so that the high-pressure compaction stage avoids the lowest viscosity or maximum flow stage of the adhesive layer; at the same time, differential temperature control in the boundary region limits the overflow of the adhesive layer to the inner circle edge, outer circle edge, and tooth groove edge, thereby helping to balance the stacking density of the surface adhesive stator core and the anti-overflow effect. Example 2 This embodiment provides a method for stacking surface adhesive stator cores suitable for applications with thin adhesive layers or a small number of laminations.

[0050] Stator laminations of the same batch were stacked to form a lamination group. The first axial pressure P1 was set to 0.05 MPa. The lamination group was heated under P1, and the change in stacking height H over time t was collected. The sampling interval Δt was 2 s. The compressibility flow index I(t) and its peak value Imax were determined based on H(t).

[0051] Before I(t) reaches Imax, the axial pressure P is kept below 0.40 MPa. Since the second axial pressure P2 in this embodiment is 1.50 MPa, 0.40 MPa is less than 0.50P2. When I(t) decreases from Imax to 0.60Imax, a second axial pressure P2 is applied for pulsed short-time compaction, with P2 being 1.50 MPa. The pulsed short-time compaction consists of two pulsed compactions, each lasting 10 seconds; a low-pressure holding phase is set between adjacent pulsed compactions, with the axial pressure during the low-pressure holding phase being 0.20 MPa and the holding time being 5 seconds.

[0052] In this embodiment, the temperature difference between the boundary area and the main bonding area is controlled at 10℃, and the width of the boundary area is 0.20mm. After the pulsed short-time compaction is completed, the axial pressure is adjusted to the third axial pressure P3, which is 0.20MPa, and the differential temperature control is released. After the boundary area reaches the curing temperature, heat preservation curing and pressure cooling are performed. In this embodiment, the heat preservation curing temperature is 140℃, and the heat preservation time is 120min. This parameter combination can be used for stamping assemblies with small adhesive flow to achieve controlled adhesive layer spreading. Example 2

[0053] This embodiment provides a method for stacking surface adhesive stator cores suitable for applications with thick adhesive layers, a large number of laminates, or where edge adhesive overflow is prone to occur.

[0054] Multiple stator laminations with adhesive surfaces are stacked to form a lamination assembly. The first axial pressure P1 is set to 0.50 MPa. The temperature is increased under P1, and the change in the stacking height H over time t is recorded. The formula is then used to...

[0055] Calculate the compressibility flow index I(t) and determine the peak value Imax through filtering. Before I(t) reaches the peak value Imax, the axial pressure P applied to the lamination group is less than or equal to 0.50P2.

[0056] When I(t) decreases from Imax to 0.20Imax, a second axial pressure P2 is applied for short-term compaction, with P2 being 4.50 MPa. The pulsed short-term compaction consists of 8 pulses, each lasting 1 second; the low-pressure holding pressure between two adjacent pulses is 1.00 MPa, and the holding time is 5 seconds.

[0057] In this embodiment, the temperature difference between the boundary area and the main bonding area is controlled at 40°C, and the width of the boundary area is 5.00 mm. The boundary temperature control component includes an inner circle temperature control component, an outer circle temperature control component, and a toothed groove temperature control component, and a cooling channel is provided in the boundary temperature control component to maintain a relatively high viscosity of the adhesive layer in the boundary area before and after short-term compaction. After the pulsed short-term compaction is completed, the axial pressure is adjusted to the third axial pressure P3, where P3 is 1.50 MPa, and the cooling effect of the boundary temperature control component is gradually reduced to raise the temperature of the boundary area to the curing temperature. Subsequently, heat preservation and curing are performed, and the pressure is released after cooling to the demolding temperature while maintaining the axial pressure. In this embodiment, the heat preservation and curing temperature is 210°C, and the heat preservation time is 10 minutes.

[0058] This embodiment enhances the constraint on the outward flow of the adhesive layer through a larger boundary temperature difference and a wider boundary temperature control area, making it suitable for stamping assemblies that are prone to adhesive overflow on the inner circle, outer circle, or groove. Example 3

[0059] This embodiment illustrates how to redetermine the pressure switching time when changing batches.

[0060] When replacing with a new batch of adhesive-coated stator laminations, take these laminations from that batch to form a lamination group. Following the method described in Example 1, heat the laminations under the first axial pressure P1, and re-collect the data on the change in stacking height H over time t. Based on H(t), determine the pressure switching time corresponding to the compressibility flow index I(t), peak value Imax, and kImax. Subsequently, when stacking subsequent lamination groups from this batch, the application of the second axial pressure P2 can be controlled based on the newly determined pressure switching time.

[0061] This embodiment can avoid deviations in pressure switching timing caused by differences in adhesive layer thickness, storage conditions, or initial fluidity between different batches of surface adhesive stator laminations.

[0062] Comparison instructions As a control, after stacking the same batch of surface adhesive stator laminations to form lamination groups, a fixed hot pressing method was used for stacking. The fixed hot pressing method is as follows: during the heating process, the data on the change of stacking height H over time t is not collected, the compressibility flow index I(t) is not calculated, and the pressure switching timing is not determined based on I(t). Instead, a continuous high axial pressure is directly applied at the preset temperature and maintained until the curing is completed; at the same time, no differentiated temperature control is applied between the boundary area and the main body bonding area.

[0063] In this fixed hot pressing method, if high axial pressure is applied to the low viscosity stage of the adhesive layer, the adhesive layer is prone to overflow along the end face, inner edge, outer edge, or groove edge; if the fixed pressure is reduced to avoid overflow, insufficient compaction between sheets may occur. Compared with this fixed hot pressing method, the present invention identifies the flow state of the adhesive layer by the compressibility flow index I(t), and sets the timing of applying 2 to 8 pulsed short-time compaction to the viscosity-increasing stage after I(t) drops from its peak value. At the same time, the flow-blocking region is formed by boundary differential temperature control, which is beneficial to balance anti-overflow adhesive and stacking density.

[0064] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for laminating a surface-adhesive stator core, characterized in that, Includes the following steps: S1. Stack multiple adhesive stator laminations to form a lamination group, wherein the adhesive stator lamination includes a stator lamination substrate and a thermosetting adhesive layer disposed on the surface of the stator lamination substrate. S2. The lamination assembly is heated under the first axial pressure P1 and the stacking height H is obtained as a function of time t. The compressibility flow index I(t) is determined based on the change data. S3. Before the compression flow index I(t) reaches the peak value Imax, the axial pressure P applied to the lamination group is kept less than the second axial pressure P2. S4. When the compressibility flow index I(t) decreases from the peak value Imax to kImax, the second axial pressure P2 is applied to the punch assembly for 2 to 8 pulsed short-time compaction cycles, where 0.20≤k≤0.60 and P2 is greater than P1. S5. In at least a portion of the processes from S2 to S4, differential temperature control is applied to the boundary region of the lamination group and the main body bonding region, so that the temperature of the boundary region is lower than the temperature of the main body bonding region. The boundary region is the region adjacent to at least one of the inner circle edge, outer circle edge, and tooth groove edge of the adhesive stator lamination. S6. After the pulsed short-time compaction is completed, the axial pressure is adjusted to a third axial pressure P3 that is less than P2, the differential temperature control is reduced or eliminated, the lamination group is heat-insulated and cured, and cooled and shaped under the condition of maintaining axial pressure to obtain the surface adhesive stator core.

2. The lamination process method for the surface adhesive stator core according to claim 1, characterized in that, The compressibility flow index I(t) is determined according to the following formula: Alternatively, it can be determined in the following discrete form: ; Where Δt is the time interval between two consecutive overlay height acquisitions. Let H(t) be the first derivative of the stacking height H(t) with respect to time t. for The stacking height at any given moment.

3. The lamination process method for the surface adhesive stator core according to claim 1, characterized in that, Before the compressibility flow index I(t) reaches its peak value Imax, the axial pressure P applied to the lamination assembly is less than or equal to 0.50P2.

4. The lamination process method for the surface adhesive stator core according to claim 1, characterized in that, The first axial pressure P1 is 0.05MPa to 0.50MPa, the second axial pressure P2 is 1.50MPa to 4.50MPa, and the third axial pressure P3 is 0.20MPa to 1.50MPa.

5. The lamination process method for the surface adhesive stator core according to claim 1, characterized in that, The duration of each pulsed short-time compaction is 1s to 20s; a low-pressure holding stage is set between two adjacent pulsed short-time compactions, the axial pressure of which is 0.20MPa to 1.00MPa and the holding time is 5s to 60s.

6. The lamination process method for the surface adhesive stator core according to claim 1, characterized in that, The differential temperature control ensures that the temperature of the boundary region is 10°C to 40°C lower than the temperature of the main bonding region, and the width of the boundary region extending from the inner circle edge, outer circle edge, or tooth groove edge towards the main bonding region is 0.20mm to 5.00mm.

7. The lamination process method for the surface adhesive stator core according to claim 1, characterized in that, The differentiated temperature control is achieved through a boundary temperature control component, which includes at least one of an inner circle temperature control component, an outer circle temperature control component, and a toothed groove temperature control component; the inner circle temperature control component is disposed adjacent to the inner circle edge, the outer circle temperature control component is disposed adjacent to the outer circle edge, and the toothed groove temperature control component is disposed adjacent to the toothed groove edge.

8. The lamination process method for the surface adhesive stator core according to claim 7, characterized in that, The boundary temperature control component includes at least one of a cooling channel, a heat-conducting insert, a heat-insulating pad, and a local temperature control pressure block.

9. The lamination process method for the surface adhesive stator core according to claim 1, characterized in that, Before the compressibility flow index I(t) begins to rise and reaches Imax, a small axial pulsating pressure or a small opening and closing displacement is applied to the lamination assembly under the condition of the first axial pressure P1 as the reference pressure; the pulsation frequency of the small axial pulsating pressure is 0.05Hz to 2Hz, and the number of pulsations is 3 to 30 times; the displacement of the small opening and closing displacement is 0.005mm to 0.050mm, and the frequency is 0.05Hz to 1Hz.

10. The lamination process method for the surface adhesive stator core according to claim 1, characterized in that, When changing the batch of stator laminations with adhesive surface, S2 is re-executed for the lamination group formed by the new batch of stator laminations with adhesive surface to redetermine the pressure switching time corresponding to the peak value Imax and kImax.

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